Browsing by Author "Huang, Xiaochuan"

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    A Polysulfone/Cobalt Metal–Organic Framework Nanocomposite Membrane with Enhanced Water Permeability and Fouling Resistance
    (American Chemical Society, 2022) Gil, Eva; Huang, Xiaochuan; Zuo, Kuichang; Kim, Jun; Rincón, Susana; Rivera, José María; Ranjbari, Kiarash; Perreault, François; Alvarez, Pedro; Zepeda, Alejandro; Li, Qilin; Nanosystems Engineering Research Center for Nanotechnology Enabled Water Treatment
    Ultrafiltration membranes are widely used in water and wastewater applications. The two most important membrane characteristics that determine the cost-effectiveness of an ultrafiltration membrane process are membrane permeability and fouling resistance. Metal–organic frameworks (MOFs) have been intensively investigated as highly selective sorbents and superior (photo) catalysts. Their potential as membrane modifiers has also received attention recently. In this study, a non-functionalized, water-stable, nanocrystalline mixed ligand octahedral MOF containing carboxylate and amine groups with a cobalt metal center (MOF-Co) was incorporated into polysulfone (PSF) ultrafiltration (UF) membranes at a very low nominal concentration (2 and 4 wt %) using the conventional phase inversion method. The resultant PSF/MOF-Co_4% membrane exhibited water permeability up to 360% higher than of the control PSF membrane without sacrificing the selectivity of the membrane, which had not been previously achieved by an unmodified MOF. In addition, the PSF/MOF-Co_4% membrane showed strong resistance to fouling by natural organic matter (NOM), with 87 and 83% reduction in reversible and irreversible NOM fouling, respectively, compared to the control PSF membrane. This improvement was attributed to the increases in membrane porosity and surface hydrophilicity resulting from the high hydrophilicity of the MOF-Co. The capability of increasing membrane water permeability and fouling resistance without compromising membrane selectivity makes the MOF-Co and potentially other hydrophilic MOFs excellent candidates as membrane additives.
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    Bi-Polymer Electrospun Nanofibers Embedding Ag3PO4/P25 Composite for Efficient Photocatalytic Degradation and Anti-Microbial Activity
    (MDPI, 2020) Habib, Zunaira; Lee, Chang-Gu; Li, Qilin; Khan, Sher Jamal; Ahmad, Nasir Mahmood; Jamal, Yousuf; Huang, Xiaochuan; Javed, Hassan; NSF Nanosystem Engineering Research Center for Nanotechnology Enabled Water Treatment
    Using a bi-polymer system comprising of transparent poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), a visible light active Ag3PO4/P25 composite was immobilized into the mats of polymeric electrospun nanofibers. After nanofibers synthesis, sacrificial PVP was removed, leaving behind rough surface nanofibers with easy access to Ag3PO4/P25 composite. The remarkable photocatalytic efficiency was attained using a PMMA and Ag3PO4/P25 weight ratio of 1:0.6. Methyl orange (MO) was used to visualize pollutant removal and exhibited stable removal kinetics up to five consecutive cycles under simulated daylight. Also, these polymeric nanofibers (NFs) revealed an important role in the destruction of microorganisms (E. coli), signifying their potential in water purification. A thin film fibrous mat was also used in a small bench scale plug flow reactor (PFR) for polishing of synthetic secondary effluent and the effects of inorganic salts were studied upon photocatalytic degradation in terms of total organic carbon (TOC) and turbidity removal. Lower flow rate (5 mL/h) resulted in maximum TOC and turbidity removal rates of 86% and 50%, respectively. Accordingly, effective Ag3PO4/P25 immobilization into an ideal support material and selectivity towards target pollutants could both enhance the efficiency of photocatalytic process under solar radiations without massive energy input.
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    Interaction of Scaling Species with Polymeric Materials
    (2023-04-21) Huang, Xiaochuan; Li, Qilin; Getachew, Bezawit A
    Polymeric membranes have been widely applied for water desalination due to their energy efficiency and relative low cost. However, the existence of scaling ions in the system and their interaction with the polymeric membranes, such as Ca2+ and SO42-, lead to the severe membrane scaling issue and the inefficient desalination performance. Membrane scaling and fouling have been the major constraint for the further improved desalination performance, which leads to the reduced water productivity and shortened membrane life. Additionally, the preferential transport of Ca2+ over monovalent ions in cation exchange membranes (CEM) results in the unstable and unsatisfactory water quality for direct portable use. Therefore, it is significant to thoroughly understand the impacts of different material properties on the interactions between scaling species and the polymeric membranes, and develop the desirable membrane materials that can meet the application needs. This study investigated the specific effects of material surface hydrophilicity and the structural property on the gypsum (CaSO4·2H2O) scaling control and particle attachment regulation, and developed a novel monovalent selective membranes that can be applied in electrodialysis (ED) for desalination and resource recovery. In the liquid environment, material surface hydrophobicity plays a very important role in gypsum scale formation. Due to the hydrophilic repulsion, increased hydrophilicity largely reduced the adhesion of gypsum particles that formed from bulk precipitation. Additionally, the material hydrophobicity strongly influenced the surface induced heterogeneous nucleation of gypsum. Without the interference of specific functional groups that can interact with Ca2+ or SO42- ions, surfaces of higher hydrophobicity promote gypsum surface nucleation, due to the reduced nucleation energy barrier. The ion adsorption on the surface also induced gypsum heterogeneous nucleation, however, the contribution was much smaller than that of hydrophobicity. Furthermore, gypsum scale formed from surface induced heterogeneous nucleation was highly irreversible, in contrast to those formed from homogeneous nucleation and bulk precipitation. These results suggest that surface induced heterogeneous nucleation is far more detrimental than homogeneous nucleation. The effects of dynamic surface coatings on particle fouling and gypsum scaling were investigated using synthesized stimuli-responsive polymer brushes. The attachment of polystyrene (PS) particles on thermos-responsive poly (N-isopropylacrylamide) (PNIPAM) was strongly influenced by the temperature, particle characteristics (i.e., size and functional groups) and the PNIPAM grafting density. PNIPAM of higher grafting density reduced the attachment of PS regardless of particle size. Less PS was attached on PNIPAM at low temperature (<33 ˚C) than that at high temperature (>33 ˚C), while the case was opposite for carboxylate PS, due to the different interactions between particles and exposed functional groups of PNIPAM. Notably, the fast dynamic structural change (every 1 min) of PNIPAM introduced by temperature switch was found to minimize the attachment of particles regardless of particle size and functional groups. Additionally, dynamic structural change also effective to remove particles that was attached within a short period of time with a removal rate of 70%. The dynamic structural change of pH-responsive poly (2-(dimethylamino)ethyl methacrylate) (PDMAEMA) was demonstrated promising for gypsum removal. PDMAEMA polymer brushes with a thickness of about 30 nm were coated on carbon nanotubes (CNT). Compared to pristine CNT, the PDMAEMA coated CNT significantly reduced the deposited gypsum due to the increased hydrophilicity. Moreover, with only 6 cycles of pH switch, over 86.4% of the gypsum was removed from the PDMAEMA coated CNT surface. As gypsum dissolution was negligible, this result indicated the important role of the dynamic structural change of PDEMA on gypsum removal. Additionally, the in-situ pH change was achieved from the water splitting with an alternating voltage (±2V) applied on the PDMAEMA-CNT. It was found 99% of the gypsum was removed with only 4 cycles of pH switch in synergy with bubble generation. A novel selective nanocomposite cation exchange membrane was synthesized to improve the monovalent/divalent permselectivity in the ED system. The membrane held a 3-layer structure including cation ion exchange polymer (CEP), Polysulfone and polyamide layer which provided the cation/anion separation, the mechanical strength and the divalent rejection function separately. The synthesized membrane demonstrated comparable electrical resistance to the commercial CEM due to the largely reduced membrane thickness. The monovalent/divalent permselectivity (e.g. Li+/Ca2+ permselectivity) achieved more than 6 even at a very low Li+/Ca2+ concentration ratio (1:10). Therefore, the synthesized membrane is promising for water desalination and resource recovery. More importantly, such membrane structure which allows the independent optimization of each functional layer provides versatile solutions to different application needs.
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    Polydopamine-assisted one-step immobilization of lipase on α-alumina membrane for fouling control in the treatment of oily wastewater
    (Elsevier, 2023) Mulinari, Jéssica; Ambrosi, Alan; Feng, Yuren; He, Ze; Huang, Xiaochuan; Li, Qilin; Di Luccio, Marco; Hotza, Dachamir; Oliveira, J. Vladimir; Nanotechnology-Enabled Water Treatment Center (NEWT)
    Covalent enzyme immobilization is generally a time-consuming and multistep procedure that uses toxic solvents and requires more than one chemical, making industrial upscaling unattractive. Using an aqueous polydopamine (PDA) solution for enzyme immobilization is a greener alternative. Usually, enzyme immobilization using PDA is performed in two steps: dopamine polymerization on the material surface followed by enzyme immobilization. A few recent studies applied a one-step strategy by mixing dopamine and enzyme in the coating solution, reducing the immobilization time, chemical consumption, and wastewater generation. This study compares the two-step and one-step approaches to immobilizing the lipase Eversa Transform 2.0 (ET2) on an α-alumina membrane. The one-step immobilization method achieved similar enzyme loading, membrane hydrolytic activity, and enzyme-specific activity to those of the two-step method. The ET2 immobilized using both strategies showed excellent fouling resistance and self-cleaning performance in oily wastewater filtration. The membrane modified by the one-step approach exhibited a lower reduction in pure water permeance after oil fouling (35%) and a higher permeance recovery (90%) than the one modified by the two-step method (40% and 74%, respectively). This better performance can be due to the higher hydrophilicity of the modified membrane and higher stability over reaction time shown by the enzyme immobilized by the one-step strategy. The higher stability can be attributed to more attachment points between the enzyme and PDA, increasing the enzyme rigidity and preventing conformational changes.
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    Selective membranes in water and wastewater treatment: Role of advanced materials
    (Elsevier, 2021) Zuo, Kuichang; Wang, Kunpeng; DuChanois, Ryan M.; Fang, Qiyi; Deemer, Eva M.; Huang, Xiaochuan; Xin, Ruikun; Said, Ibrahim A.; He, Ze; Feng, Yuren; Walker, W. Shane; Lou, Jun; Elimelech, Menachem; Huang, Xia; Li, Qilin; NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment
    Membrane separation has enjoyed tremendous advances in relevant material and engineering sciences, making it the fastest growing technology in water treatment. Although membranes as a broad-spectrum physical barrier have great advantages over conventional treatment processes in a myriad of applications, the need for higher selectivity and specificity in membrane separation is rising as we move to target contaminants at trace concentrations and to recover valuable chemicals from wastewater with low energy consumption. In this review, we discuss the drivers, fundamental science, and potential enabling materials for high selectivity membranes, as well as their applications in different water treatment processes. Membrane materials and processes that show promise to achieve high selectivity for water, ions, and small molecules—as well as the mechanisms involved—are highlighted. We further identify practical needs, knowledge gaps, and technological barriers in both material development and process design for high selectivity membrane processes. Finally, we discuss research priorities in the context of existing and future water supply paradigms.
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    Ultrahigh resistance of hexagonal boron nitride to mineral scale formation
    (Springer Nature, 2022) Zuo, Kuichang; Zhang, Xiang; Huang, Xiaochuan; Oliveira, Eliezer F.; Guo, Hua; Zhai, Tianshu; Wang, Weipeng; Alvarez, Pedro J.J.; Elimelech, Menachem; Ajayan, Pulickel M.; Lou, Jun; Li, Qilin; NSF Nanosystems Engineering Research Center Nanotechnology-Enabled Water Treatment
    Formation of mineral scale on a material surface has profound impact on a wide range of natural processes as well as industrial applications. However, how specific material surface characteristics affect the mineral-surface interactions and subsequent mineral scale formation is not well understood. Here we report the superior resistance of hexagonal boron nitride (hBN) to mineral scale formation compared to not only common metal and polymer surfaces but also the highly scaling-resistant graphene, making hBN possibly the most scaling resistant material reported to date. Experimental and simulation results reveal that this ultrahigh scaling-resistance is attributed to the combination of hBN’s atomically-smooth surface, in-plane atomic energy corrugation due to the polar boron-nitrogen bond, and the close match between its interatomic spacing and the size of water molecules. The latter two properties lead to strong polar interactions with water and hence the formation of a dense hydration layer, which strongly hinders the approach of mineral ions and crystals, decreasing both surface heterogeneous nucleation and crystal attachment.